CEL Code reset?

[jmonica]

Hi, I have several OBD2 codes I started chasing this past weekend. P0138, 140, 455 443, 420, 449. I replaced the purge valve solenoid a 02 sensor, fixed a leak in filler neck and replaced an exhaust gasket that was leaking badly.
My question is should I clear the codes or will they go away after enough engine cycles?

I prefer the see if they clear themselves to indicate problem resolution, but not sure if they will in fact clear automatically eventually?

Thank You

 

[christo829]

They should clear with anywhere between three to five full driving cycles.

Cheers-

Chris

 

[TollKeeper]

My research on that shows 30-60 engine cycles with no CEL malfunctions reported.

 

[christo829]

Hm... When I haven't bothered clearing a code but have fixed the issue, it's taken between three and five full driving cycles (cold start, run to operating temp and closed loop, like a good highway run, then shut down and cool off) before the code clears and doesn't show as active or pending.

Maybe what I'm calling a "driving cycle" and your "engine cycle" are different critters? I'll have to go open the dead tree manuals and see if I'm phrasing it wrong.

 

[jmonica]

Hm... When I haven't bothered clearing a code but have fixed the issue, it's taken between three and five full driving cycles (cold start, run to operating temp and closed loop, like a good highway run, then shut down and cool off) before the code clears and doesn't show as active or pending.

Maybe what I'm calling a "driving cycle" and your "engine cycle" are different critters? I'll have to go open the dead tree manuals and see if I'm phrasing it wrong.

This is what I'm wondering as well and it is what prompted me to post the question here. Something else I read said something like 30-40 cycles. So I think maybe my interpretation of a cycle is wrong. If I had to wait that long to see if the problem is solved, I'm afraid the CEL would never go out as because chances are a new seperate code/problem will crop up during that time on my jalopy. Thanks Guys for responding.

If anyone know what a "Drive Cycie" consists of, can you please let me know? I thought it was as Christo829 described. Thanks again.

 

[TequilaWarrior]

Honestly, you're probably better off clearing the codes regardless of the number of driving cycles. If any reappear, or if new appear, you should have plenty of information to work from.

A quick and lazy google search shows a myriad of answers to "how long until my OBD2 codes reset themselves after a fix" suggest between either 10 to 20 "cold starts" and/or 50 to 100 miles.

My suspicion is that it depends on the codes. There is a vast difference between the stupid "gas cap loose" code (which some vehicles have a specific light for these days) and the "random misfire" code. One is fixed by getting out and tightening your gas cap, the other by throwing random parts at the engine while burning your checkbook.

 

[Mooseman]

You're better off clearing them so you can quickly see if the parts you threw at it fixed your issues. If they didn't, the codes will return quickly.

 

[jmonica]

They should clear with anywhere between three to five full driving cycles.

Cheers-

Chris

Thanks for replying. I've driven I think 4 drive cycles over 50 miles so I'm hoping that on my way home the code clears. I'm trying to get it inspected this weekend so I don't want to clear the codes which is an automatic failure. Hoping the light goes away on its own and I can get the inspection done.

 

[jmonica]

You're better off clearing them so you can quickly see if the parts you threw at it fixed your issues. If they didn't, the codes will return quickly.

Thanks Moose. I did throw an O2 sensor and a Evap vent valve at it and that seems to have gotten rid of a lot of the codes. 9 to be exact. I still have two codes that were there after I reset but before i replaced the purge valve a couple of days ago and those are my final two codes. Want to get it inspected Saturday, so I'm trying to see if the CEL will go away before then without having to clear the codes and go through several days of drive cycles before I can get it inspected. The purge valve basically crumbled in my hand when I went to remove it so I'm fairly sure that was the problem. The hoses and electrical connector still looked good.

 

[TequilaWarrior]

Thanks for replying. I've driven I think 4 drive cycles over 50 miles so I'm hoping that on my way home the code clears. I'm trying to get it inspected this weekend so I don't want to clear the codes which is an automatic failure. Hoping the light goes away on its own and I can get the inspection done.

CEL Reset should not cause you to fail your inspection - at least it doesn't in my county. I literally reset mine immediately before taking it to be inspected, regardless of whether codes are set, pending, or otherwise. Of course, there is no specific emissions testing here even though they failed me on the Catholic muffler I had (holier than it should have been).

 

[budwich]

Its not usually the clearing of the codes that cause the problem, its the reset of the monitors which have to be running usually for a pass and those take drive cycles to get them to come back up.

 

[jmonica]

Its not usually the clearing of the codes that cause the problem, its the reset of the monitors which have to be running usually for a pass and those take drive cycles to get them to come back up.

Yes that's exactly the situation. It's not the lack of codes, it's the monitors not reporting until enough drive cycles have been performed after a reset. The result is the same, they can't get a reading, but I should have explained it more clearly. Thanks

 

[jmonica]

Thanks. Here in NJ, emissions is the only test they check for these days. They used to check brakes,, headlights, etc, now if you pass emissions you pass. A lot of people seem to be hung up on the wording I used when I write that post so let me reword what I was trying to say.

I've been though this with other vehicles here in NJ. If you clear your check engine codes with a code reader, you have to complete a full drive cycle which involves traveling at certain speeds for certain distances, slowing down and driving certain distances etc, before the inspection station testing machine will perform whatever it is they consider a full test. If you clear the codes, and then immediately drive to the inspection station before completing the necessary drive cycle(s), the inspection station will indicate that they are unable to scan your vehicles computer and thus unable to pass you. In other words, they ain't falling for no banana in their tailpipe.

Otherwise, what would prevent anyone from clearing their Check Engine light immediately before pulling into inspection and getting inspected before their vehicle's computer has had a chance to report whatever problems it is having?

So I guess my point is that, yes clearing the codes won't prevent you form passing the test, but it WILL prevent your car from being able to to be inspected unless and until you've completed the required drive cycle, which by then the computer will have had time to test for malfunctions and turn on the CEL again. There's a big sign in front of the inspection station near my house that says "Check Engine Light = Fail".

 

[Mooseman]

Do they allow one test to not be completed to pass? When we used to have testing here, they allowed one test to not be ready. Likely did that because the Evap test usually took forever to complete, especially in winter.

 

[jmonica]

Do they allow one test to not be completed to pass? When we used to have testing here, they allowed one test to not be ready. Likely did that because the Evap test usually took forever to complete, especially in winter.

That's a very good question. I will find out and post back. The only reason I know about clearing codes and not being able to be tested is I repaired my car, cleared the codes and went the next day to get tested. The only I found the lady doing thectezt daud was, we can't read your computer. I knew why but I played dumb and and asked what she me meant, why not? And she said she didn't know, that there must be something wrong with my car and told me to take it to a mechanic.

A failed or incomplete test does buy you another 30 days, but I'm not sure how many times you can get that 30 day extension sticker, if you keep getting retested and failing.

I did the smoke test today, nothing.

When I first started the test I saw smoke pouring out of the back and thought i had found the problem but the vent valve was open and just venting the smoke.

I had an emergency and had to button it up and drive some place in a hurry so I didn't get a chance to keep troubleshooting. But I could not find any leaks. It socks because I was finally making progress and now have to start over again.

I have to run out, but I really need your guys advice based on what I discovered so far.

I will have to post again and hope someone can provide the guidance I need. I have some ideas bit need to confirm my plan to isolate will work before I try it so I'm not trusting for no reason.

I know this st7ff is child's play to you, but it my first time troubleshooting the evap system so I'm still a little fuzzy on a couple of things. I really don't want to smoke the PCM so I'm being overly cautious.

Thank You!

 

[Mooseman]

We will need to know which codes you still have.

EVAP problems are not child's play for anyone. It's always a bitch to work on.

 

[jmonica]

We will need to know which codes you still have.

EVAP problems are not child's play for anyone. It's always a bitch to work on.

So I do not see any smoke leaks any place but feel I need to explain what happened when I did the test.
I started the smoke and could almost immediately see smoke just dumping out of the rear of the vehicle. Unfortunately it turned out that the smoke was coming directing from the Vent vavle.

This is when I got that emergency phone call to pickup my son so I had to end my testing and button everything up. Very aggravating as I've been dying to get to the bottom of this for two weeks now.

Anyway before I shut it down, I closed the vent valve with the scanner and didn't see any smoke at all. It's not really a valid test though. I'm not even 100% sure the machine was pumping smoke at that moment to be honest.

I hate that I'm so stupid in regard to this problem.

For one thing, I replaced the vent valve but I didn't test it and didn't test for voltage at the wire when I did it. I did both of those things for the purge valve but not the vent valve.

So I need to check the valve and the circuit for voltage during my next session.

So here are my first three dumb questions which will really help shed some light on this.

A) the scanner has a test that appears to seal the evap system and it says the system passes that test. I don't know if it actually tests it for being sealed or if it just does what's required to seal the evap system and so it reports it as sealed if that makes sense? It's my first time using this scanner.

B) the scanner is bi-directional. It gives me the option to operate the vent and purge valves. Using the purge valve as an example, the wiring diagram indicates a constant 12v to the valve, which I have, and the PCM grounds the other wire to operate the valve when needed.
That leads me to think that if I use the scanner to operate the valve, then I should read a good ground on the other wire connected to it when it's activated? Shouldn't I? Or am I not understanding how it works?

C) The current code is P0449. The online description reads: "Evaporative System Vent Control Circuit Malfunction". I thought mine read "vent control valve open circuit" The word "circuit" leads me to believe it's electrical. Is that the case or am I over analyzing the wording?

I'm really jumping the gun on these questions I think. Prior to checking and cleaning every ground I could find, I had codes P0443 and P0449. Although both evap related, I haven't instance online where someone had just these two specific codes at the same time. That's why I started to think I maybe had a bad ground some place.

So after cleaning all of the grounds i could find, I took it for a drive and i was then only getting P0449. But I don't know if I drove it long enough to generate the 0443 code or if it's actually gone.

So I need to drive it some more and see. It didn't take long to get the 443 code after the few times a reset it, so I don't know how long before I can assume that code is no longer.

After writing all of this I think I need to
1) drive some more then check for codes other than 0449
2) test for 12v at the vent valve
3) I there's voltage, although the valve is new, I need to test it. I've gotten bad parts off the shelf before and this one cake right from evil bay.

Btw... cleaning the grounds did fix my wiper / washer problem. Both work again.

Thank you

 

[mrrsm]

Your Profile does not indicate the "Year of Manufacture" for your Envoy... but a quick visit to @Mooseman 's "Need Manuals?" Thread will afford you the chance to Download and Save the one related to your version.

After you have it tucked away and unzipped... Look up the Chapter & Verse in the EVAP areas of the Digital Manual and find the Diagnostic Procedures Chart therein. Even though it is designated specifically for use with the "GYMKO" Tech 2... You are mostly just interested in the "Step-By-Steps" involved for checking things out in a certain order and with certain actions needed for each test phase.

For those following along with interest and in possession of their OWN Tech 2... THIS PDF provides the particular Function and Key Pad Touches for all of the Diagnostic Procedures... ANOTHER great PDF to keep in your "Mechanic's Library":

 

[Mooseman]

A circuit malfunction could involve the valve itself. Like you, and others, have said, just because it's new doesn't mean it's good, especially if it's CCC from eBay. Check for voltage and then check the valve.

Activating the valve with the engine not running should allow you to hear the valve click. And closing both valves, you should see pressure build inside the tank, which would indicate you don't have a leak or faulty valve. And reopening the vent valve would release this pressure.

 

[jmonica]

A circuit malfunction could involve the valve itself. Like you, and others, have said, just because it's new doesn't mean it's good, especially if it's CCC from eBay. Check for voltage and then check the valve.

Activating the valve with the engine not running should allow you to hear the valve click. And closing both valves, you should see pressure build inside the tank, which would indicate you don't have a leak or faulty valve. And reopening the vent valve would release this pressure.

Awesome, thank You Mooseman. As always, you're the best. I'm going to I tried to listen for the valve when I activated it and did not hear anything but it's at the rear and I wasn't sure if I'd be able to. I CANNOT wait to get into it this weekend. This whole working full time thing can be a real inconvenience! Thank You again and I will report my findings on the off chance it may help someone else.

I'm also going to have a look at the live data just to see what, if anything it reveals.
I'll get to the bottom of this yet!

Thank You again for the help.

Someone also suggested checking the fuel trims which I will. I just need to find out what they should be. I'd guess if I see him be that's significantly different, it would indicate a problem.

When I start the car after driving it for an hour or 50 miles or more, there's a patch of black stuff that comes out if the exhaust pipe. I'm assuming it's carbon from running so rich.

 

[jmonica]

Your Profile does not indicate the "Year of Manufacture" for your Envoy... but a quick visit to @Mooseman 's "Need Manuals?" Thread will afford you the chance to Download and Save the one related to your version.

After you have it tucked away and unzipped... Look up the Chapter & Verse in the EVAP areas of the Digital Manual and find the Diagnostic Procedures Chart therein. Even though it is designated specifically for use with the "GYMKO" Tech 2... You are mostly just interested in the "Step-By-Steps" involved for checking things out in a certain order and with certain actions needed for each test phase.

For those following along with interest and in possession of their OWN Tech 2... THIS PDF provides the particular Function and Key Pad Touches for all of the Diagnostic Procedures... ANOTHER great PDF to keep in your "Mechanic's Library":

Thank You for the info. I've updated my profile with the year of the vehicle. 2006
I have previously downloaded the manuals mooseman has posted. I just haven't taken the time to read through them like I should.
I didn't realize there were step by step diagnostic procedures included. I'm all over that.
I think that's been a big part of why I haven't found the problem because I've been checking this or checking that l and not following a logical order to rule things out as I go.

I'm going to start from scratch, follow the troubleshooting procedures to help isolate the problem and get this thing solved.

I will post my findings.

I appreciate your help with this very much!

 

[jmonica]

A circuit malfunction could involve the valve itself. Like you, and others, have said, just because it's new doesn't mean it's good, especially if it's CCC from eBay. Check for voltage and then check the valve.

Activating the valve with the engine not running should allow you to hear the valve click. And closing both valves, you should see pressure build inside the tank, which would indicate you don't have a leak or faulty valve. And reopening the vent valve would release this pressure.

Ugg.. Hi. So I'm still getting P0449 and P0443. I'm working on the P0449 vent control valve problem.
I have run a smoke test and found no leaks.

Today, I am checking electrical. At the Vent valve connector, the good news is that the PCM is throwing a ground when the circuit is activated. I pulled the valve (which is new), and the valve operates as is should. I seals when voltage is applied.

The problem I discovered (and I was excited because up until right now, I haven't been able to find anything wrong), I discovered with the key on, there's no voltage at the vent valve connector. From what I can tell, there should be a constant 12v to it, and the PCM grounds it to activate it.

There's a short extension to the wire connector above the tank. no power to that either.

I've checked all of the fuses, but I can't figure out which fuse the vent valve is on,

So now I have to try to trace the wire I guess.

Pulling the tank is not going to be an option in my current situation. So I am trying to find the wire from the fuse block and start tracing it that way, to the back of the vehicle, but I can't figure it out.

I'm dying on this. I at least feel like I've made progress but now I'm stuck trying to figure out which wire it is and trying to trace it so see where the break in the connection is. I am very tempted to run a new wire, but I'm not going to do that.

Does anyone having any suggestions? I sure could use some help. I believe the fuse is number 28, but not sure I'm right.

Thought about maybe buying a tool to help trace the wire (the type with a tone?).

Thank You in advance!!!

 

[budwich]

my read is the fuse is 26. It should have voltage all the time (B+).

 

[mrrsm]

... and MORE from @budwich via this On Topic Thread from TV...

P0455 and No power to Vent Valve

www.trailvoy.com

Also... Try Replacing ALL of the Fuses in ANY of the EVAP Circuits (...eliminating any possible Micro-Cracked Fuse Element(s)...) AFTER Un-Bolting the Galvanized Fuse Block Fasteners, Un-Plugging the Block Segments... and then thoroughly Spraying Out the Fuse Blocks with CRC Electrical Cleaning "Lectro-Motive" Solvent and Re-Assemble:

Amazon.com: CRC 05018 Lectra-Motive Electric Parts Cleaner - 19 Wt Oz.: Sports & Outdoors

Buy CRC 05018 Lectra-Motive Electric Parts Cleaner - 19 Wt Oz.: Electrical Cleaners - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[jmonica]

... and MORE from @budwich via this On Topic Thread from TV...

P0455 and No power to Vent Valve

www.trailvoy.com

Also... Try Replacing ALL of the Fuses in ANY of the EVAP Circuits (...eliminating any possible Micro-Cracked Fuse Element(s)...) AFTER Un-Bolting the Galvanized Fuse Block Fasteners, Un-Plugging the Block Segments... and then thoroughly Spraying Out the Fuse Blocks with CRC Electrical Cleaning "Lectro-Motive" Solvent and Re-Assemble:

Amazon.com: CRC 05018 Lectra-Motive Electric Parts Cleaner - 19 Wt Oz.: Sports & Outdoors

Buy CRC 05018 Lectra-Motive Electric Parts Cleaner - 19 Wt Oz.: Electrical Cleaners - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

View attachment 108524

So i just logged on to post a discovery and it just so happens, that you hit the nail on the head. I didn't bother trying to trace the wire above the tank etc. No work had been done to anything tat could have pinched the wire and I just knew that wasn't the problem.

I started checked fuses and relays etc. I gave up but, before I did, checked for voltage at the vent valve wire again one last time and al of a sudden it has 12v.

I plugged the valve back in and activated it via the scanner and heard the click / clunk of it opening and closing.

Took it for a short drive and codes returned. Got home and checked the wire again, nothing.

So I went back to the fuse block and the wiring near it and tried moving things to get voltage at the wire. Nothing. About to give up, I leaned over the engine and had my hand on top of the fuse block and heard the valve click.

So I started checking fuses again, low and behold, fuse #26 (10amp) if I put a little pressure on it pushing it towards the front of the car, I had no voltage. Pressure towards the back, I had voltage.

YES! I kind of have two problems though. First off, the fuse is bad. It's not blown, but one of the legs, you can wiggle back and forth, causing a fault. OK, so I replaced it, but the new fuse feels loose and I still have the situation where if I push it one way, I have voltage at the wire and vice versa.

So I am fairly sure I can fix it, thankfully. I just need to close the connections in the fuse block to tighten it up so the fuse is tight and god willing I will finally have solved the problem!

Thank You everyone for your help. Once I fix the fuse and test drive the vehicle, I will post back whether or not the p0443 and p0449 codes are gone. I've gotten excited like this before when I thought I had fixed a problem and turned out it wasn't fixed after all. I feel good about this one though given the other testing I've done. Checking components, PCM, smoke test etc... Fingers crossed!

 

[jmonica]

my read is the fuse is 26. It should have voltage all the time (B+).

Thank You Budwich! It was #26 AND your old post on that other website turned out to be my problem. A defective fuse. Not blown, but the legs were loose causing an intermittent fault.

It's funny because I actually discovered the bad fuse before reading your reply or your other post about bad fuses. So I came inside to post what I had found. When I saw your post about the fuse number being #26, I went back outside and was overjoyed to see that the bad fuse I had found was in fact #26!

 

[jmonica]

... and MORE from @budwich via this On Topic Thread from TV...

P0455 and No power to Vent Valve

www.trailvoy.com

Also... Try Replacing ALL of the Fuses in ANY of the EVAP Circuits (...eliminating any possible Micro-Cracked Fuse Element(s)...) AFTER Un-Bolting the Galvanized Fuse Block Fasteners, Un-Plugging the Block Segments... and then thoroughly Spraying Out the Fuse Blocks with CRC Electrical Cleaning "Lectro-Motive" Solvent and Re-Assemble:

Amazon.com: CRC 05018 Lectra-Motive Electric Parts Cleaner - 19 Wt Oz.: Sports & Outdoors

Buy CRC 05018 Lectra-Motive Electric Parts Cleaner - 19 Wt Oz.: Electrical Cleaners - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

View attachment 108524

Thank You for all of your help on this one. I appreciate you sticking with me!

Next challenge, I have to replace the rack and pinion and going to replace the backing plates on all four wheels. And honestly I'm not looking forward to it, but we do what we have to I guess.

Thank You again!

 

[mrrsm]

"So Shines a Good Deed... In a Weary World..." - Willie Wonka

 

[budwich]

So i just logged on to post a discovery and it just so happens, that you hit the nail on the head. I didn't bother trying to trace the wire above the tank etc. No work had been done to anything tat could have pinched the wire and I just knew that wasn't the problem.

I started checked fuses and relays etc. I gave up but, before I did, checked for voltage at the vent valve wire again one last time and al of a sudden it has 12v.

I plugged the valve back in and activated it via the scanner and heard the click / clunk of it opening and closing.

Took it for a short drive and codes returned. Got home and checked the wire again, nothing.

So I went back to the fuse block and the wiring near it and tried moving things to get voltage at the wire. Nothing. About to give up, I leaned over the engine and had my hand on top of the fuse block and heard the valve click.

So I started checking fuses again, low and behold, fuse #26 (10amp) if I put a little pressure on it pushing it towards the front of the car, I had no voltage. Pressure towards the back, I had voltage.

YES! I kind of have two problems though. First off, the fuse is bad. It's not blown, but one of the legs, you can wiggle back and forth, causing a fault. OK, so I replaced it, but the new fuse feels loose and I still have the situation where if I push it one way, I have voltage at the wire and vice versa.

So I am fairly sure I can fix it, thankfully. I just need to close the connections in the fuse block to tighten it up so the fuse is tight and god willing I will finally have solved the problem!

Thank You everyone for your help. Once I fix the fuse and test drive the vehicle, I will post back whether or not the p0443 and p0449 codes are gone. I've gotten excited like this before when I thought I had fixed a problem and turned out it wasn't fixed after all. I feel good about this one though given the other testing I've done. Checking components, PCM, smoke test etc... Fingers crossed!

the "fix" on the loose fuse is to "gently" twist the legs a bit so as to have more "plane" of "potential contact"... like a barber's pole but not that twisted ... about 1/8 turn or so.

 

[jmonica]

... and MORE from @budwich via this On Topic Thread from TV...

P0455 and No power to Vent Valve

www.trailvoy.com

Also... Try Replacing ALL of the Fuses in ANY of the EVAP Circuits (...eliminating any possible Micro-Cracked Fuse Element(s)...) AFTER Un-Bolting the Galvanized Fuse Block Fasteners, Un-Plugging the Block Segments... and then thoroughly Spraying Out the Fuse Blocks with CRC Electrical Cleaning "Lectro-Motive" Solvent and Re-Assemble:

Amazon.com: CRC 05018 Lectra-Motive Electric Parts Cleaner - 19 Wt Oz.: Sports & Outdoors

Buy CRC 05018 Lectra-Motive Electric Parts Cleaner - 19 Wt Oz.: Electrical Cleaners - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

View attachment 108524

Well the p0449 code is solved but the p0443 code is still there. I didn't expect the fix for 449 to fix this as well, but I was secretly hoping it would. I don't know if the purge and vent valves are on teh same fuse or not. Tomorrow I'm going to check the purge valve has power and that the PCM is triggering or activating the purge valve. It had 12v at it last time I checked and I know the valve is good. The only thing I didn't check is that the PCM is able to ground it, which I can check the same way I checked the vent valve.
If it does, and if it has power, then I'm really stuck and won't know where to go from there. BUT some how, some way, I will eventually figure it out if it kills me.
I'd give my right arm for a nice garage to work in, instead the tiny little thing I work in now, I have about 6-8" on both sides of the car and about 16 inches in front of it to move around.

 

[budwich]

they both share the same fuse... :-( but doesn't mean anything... measuring for voltage is always the final "say". BUTTTTT having said that, the vent circuit "loops" back thru the fuse box to get the ground.... what's that saying "where there is one roach, there are others nearby"....

 

[mrrsm]

And with an eye towards... "Leaving NO Stone Un-Turned..." Have a look at THIS Thread... Just In Case...

Under-Hood Vermin Infestation Issues

An off shoot of the many problems that the COVID-19 Corona Virus Pandemic brought along is the fact that many of our vehicles… NOT just the GMT-360s and GMT-400-800 Vehicles have had to be parked for longer than ordinary time frames. For some of us, depending upon the region of the countries...

gmtnation.com

 

[jmonica]

Thank You Budwich! It was #26 AND your old post on that other website turned out to be my problem. A defective fuse. Not blown, but the legs were loose causing an intermittent fault.

It's funny because I actually discovered the bad fuse before reading your reply or your other post about bad fuses. So I came inside to post what I had found. When I saw your post about the fuse number being #26, I went back outside and was overjoyed to see that the bad fuse I had found was in fact #26!

Hey Guys. So I am getting closer! This morning, I pulled the purge valve connector. inserted some test leads and have voltage and the PCM is controlling it as it should. The scanner increases the percentage the valve is opened by increments of 10%. I went through them all, and I'm fairly sure its working correctly because my test light intensified with each step until it was at full brightness at 100% open. SO great its working, but damn, now what? I checked the connector, it looks ok. So now I'm stuck. I had tested the valve before installing it and it was working fine.
So I decided to try to hear it click with everything hooked up (hoses and wires). I placed a long extension on it and put my ear to it while activating it with the scanner. At first, nada. I repositioned myself and all of a sudden, the valve started making noise. I press down on the top of it and it buzzes. The sound intensifies as I open it more and more with the scanner.

OK, progress. So now I have to see if it's the wire connection or if the valve is jacked up ion some way.

My big question I hope someone can answer now is, should I really be hearing that thing as it's operating? This sounds like a stupid question as I am writing it, but given it appears to be operating as teh sound changes etc, I feel like its louder that it should be. I sound like an idiot. When I bench tested it, I just put 12v through it, it clicked and I blew through it to check to make sure the solenoid was blocking air flow and it sure as heck wasn't making the sound it was making when I test it in the car now but I don't know if that's only because I am applying power to it in steps for lack of a better term. Someone had also mentioned that it was activated with a pulse I believe. I can confirm that the test light was also pulsing when activating it. I really wish I had more experience, someone here with experience who tell me if it is normal for it to sound like it does, or do I have a jacked up valve. I am going to work on the loose connection problem and I guess see what happens. The goal being to get it to react to the scanner commands without having to press on it.

Sorry for rambling. I don't have anyone to bounce things off, of as I'm a fairly lonely person, so sometimes just writing this stuff out and thinking about it as I type, helps me sort through it. I wish I could post a sound file so you guys could hear the sound its making and tell me if it sounds normal. I also wish I had a known good one to compare it it to. Tis is my second one. I threw the original out, I replaced it with a CCC eBay one, still had the code then bought another new from AZ and tested it and that's what's in the car now. I really don't want to buy another just for comparison purposes. Sorry for boring everyone. Thank You!

 

[budwich]

good news .... sort of. Not sure I follow your testing BUT.... the "simple test" would be to take the valve off the tank, leave the connector connected / powered. Activate the valve with your nice new scanner... as you have done but now listen closely to valve. Maybe your hearing without the "mechanic's aid" ain't so good... Further, as you change your scanner level, blow into the valve... does the air flow change?

I suspect that the valve is working... and you are hearing the "chop" of the 12v. The solenoid is not being "punched open"... it is being "controlled" so that is only opens to a level specified. Ie. 50% or what ever.

 

[jmonica]

Hey Guys. So I am getting closer! This morning, I pulled the purge valve connector. inserted some test leads and have voltage and the PCM is controlling it as it should. The scanner increases the percentage the valve is opened by increments of 10%. I went through them all, and I'm fairly sure its working correctly because my test light intensified with each step until it was at full brightness at 100% open. SO great its working, but damn, now what? I checked the connector, it looks ok. So now I'm stuck. I had tested the valve before installing it and it was working fine.
So I decided to try to hear it click with everything hooked up (hoses and wires). I placed a long extension on it and put my ear to it while activating it with the scanner. At first, nada. I repositioned myself and all of a sudden, the valve started making noise. I press down on the top of it and it buzzes. The sound intensifies as I open it more and more with the scanner.

OK, progress. So now I have to see if it's the wire connection or if the valve is jacked up ion some way.

My big question I hope someone can answer now is, should I really be hearing that thing as it's operating? This sounds like a stupid question as I am writing it, but given it appears to be operating as teh sound changes etc, I feel like its louder that it should be. I sound like an idiot. When I bench tested it, I just put 12v through it, it clicked and I blew through it to check to make sure the solenoid was blocking air flow and it sure as heck wasn't making the sound it was making when I test it in the car now but I don't know if that's only because I am applying power to it in steps for lack of a better term. Someone had also mentioned that it was activated with a pulse I believe. I can confirm that the test light was also pulsing when activating it. I really wish I had more experience, someone here with experience who tell me if it is normal for it to sound like it does, or do I have a jacked up valve. I am going to work on the loose connection problem and I guess see what happens. The goal being to get it to react to the scanner commands without having to press on it.

Sorry for rambling. I don't have anyone to bounce things off, of as I'm a fairly lonely person, so sometimes just writing this stuff out and thinking about it as I type, helps me sort through it. I wish I could post a sound file so you guys could hear the sound its making and tell me if it sounds normal. I also wish I had a known good one to compare it it to. Tis is my second one. I threw the original out, I replaced it with a CCC eBay one, still had the code then bought another new from AZ and tested it and that's what's in the car now. I really don't want to buy another just for comparison purposes.

good news .... sort of. Not sure I follow your testing BUT.... the "simple test" would be to take the valve off the tank, leave the connector connected / powered. Activate the valve with your nice new scanner... as you have done but now listen closely to valve. Maybe your hearing without the "mechanic's aid" ain't so good... Further, as you change your scanner level, blow into the valve... does the air flow change?

I suspect that the valve is working... and you are hearing the "chop" of the 12v. The solenoid is not being "punched open"... it is being "controlled" so that is only opens to a level specified. Ie. 50% or what ever.

HI. I should have described what I was doing better. With or without the hearing aid, I could hear the valve, only if i pressed on the top of it. If I let go, it wasn't working at all. It was only because I had touched the top of it with the extension to listen to it, that I discovered a loose connection and could hear the valve working, without using the extension to listen to it.

I de-pinned the connector, cleaned everything, pinched the connectors so they were tight and re-assembled. That solved the connection problem, and I "believe" has fixed the problem. I drove the same route that fired off the CEL light in teh past. It wouldn't come on until I drove it until warm. then stopped and restarted the engine and about 15 second later the light would come on with the P0443 code. I've been re-creating that scenario for two weeks now to see if the problem was resolved and today is the first time the light hasn't come back on after clearing the codes. So I drove it again just to make sure and still no CEL!

I rescanned it when I got home and now I have a P0171 code indicating a lean condition. That's the first time I've seen that code, but I don't get a CEL, (yet) so at least that's something.

I'm going to drive it to work this week and now lucky me, I have yet another DTC to diagnose next weekend. And who knows what other codes will popup before then.

Thank You again for your all of your help!

 

[mrrsm]

For anyone following along and having Similar Diagnostic Questions...

(1) Before attempting any Tests... Start by First Measuring your Battery (B+) Voltage and establish a Base Line. Remember... Battery Voltage is NOT System Voltage. Ordinary, Nominal Voltage is above 12.5 Volts DC.

(2) VVTs, EFIs, Fuse Box Relays, SAIS and Starter Solenoids are ALL just THAT... SOLENOIDS. There is NOTHING Subtle about How Solenoids WORK.

(3) As Electro-Magnetic Devices... Their Speed and Reaction performances are occurring at "The Speed of Light" (Well... With Collapsing Magnetic Fields... Almost) and are responsive to the Size of their Movable Iron or Steel Cores... Plus...The Amount of Current moving through their Circuits... Plus.... the Number of Windings of Wire present in their encircling Copper Coils.... Plus... Being modified by the Length or Distance they must Travel before they Mechanically either Close Relay Contacts or Close - Open a Valve Segments inside of any Device... say like an EGR (Exhaust Gas Re-Circulation) Valve that may have as many as THREE Separate Solenoids.

(4) Consequently, the Level of Sound created by their activation will vary depending upon what their intended functions are...Plus... How Rapidly and How Often they must perform their Activities.

(5) So... Relying upon any "Decibel Level" emanating out or any of these Solenoid Devices would be an unreliable way to figure out whether or not they are performing properly.

(6) However... If you can HEAR the Activation as it happens when directed by say... A Bi-Directional Instruction sent either from and to either the PCM during its timely Commands....or...coming from a Deliberate Test initiated from a GOOD Bi-Directional Scan Tool... If you can HEAR any activation...THAT should indicate that the Solenoid is Working.

(7) The Last Issue for Modern Electronically Controlled Vehicles ...is PWM...or Pulse Width Modulation frequently used to rapidly turn Solenoids On and Off depending upon the demands required by the PCM and the prevailing operational conditions going on.

(8) The entire reason for having these Fluid and Vapor Valves under the watchful gaze of the PCM is to prevent as much as possible, the escape of Fuel, Oil and Incomplete Combustion VOCs (Volatile Organic Compounds) from escaping and getting out into the Atmosphere. The idea is to either Capture and Store them temporarily inside of a Canister filled with pellets of Carbon... or simply re-route them directly back through the Air Stream and into the Engine to be burned as part of the normal Four Stroke Combustion Cycle.

(9) THINK ABOUT THE PHYSICAL SYSTEM AND ITS COMPONENTS IN YOUR MIND... and then logically examine ALL of them in the Order they Come On Line... and your Diagnosis will be Thorough, Complete... AND much more likely to put you in the EXACT Place where the Failure is occurring ... Like an Internally Stretched or Broken Wire that Touches when the SUV is COLD... but separates and Breaks the Circuit when the SUV is HOT...Or...Vice Versa!

(10) Try using a Simple, Inexpensive Short, Open or Broken Circuit Continuity Tracing Kit that will let you connect a Transceiver at the Circuit Suspect Wire Point of Origin... and then LISTEN to the Second Portion of the Device as it Senses the Invisible... and allows you to Locate precisely where the Continuity of the activated Wire STOPS. Like THIS Kit that You can also use to Duplicate THIS Demonstration on Your TRAILBLAZER - ENVOY:

Available on Amazon via THIS GMT Nation Link:

Amazon.com

 

[jmonica]

For anyone following along and having Similar Diagnostic Questions...

(1) Before attempting any Tests... Start by First Measuring your Battery (B+) Voltage and establish a Base Line. Remember... Battery Voltage is NOT System Voltage. Ordinary, Nominal Voltage is above 12.5 Volts DC.

(2) VVTs, EFIs, Fuse Box Relays, SAIS and Starter Solenoids are ALL just THAT... SOLENOIDS. There is NOTHING Subtle about How Solenoids WORK.

(3) As Electro-Magnetic Devices... Their Speed and Reaction performances are occurring at "The Speed of Light" (Well... With Collapsing Magnetic Fields... Almost) and are responsive to the Size of their Movable Iron or Steel Cores... Plus...The Amount of Current moving through their Circuits... Plus.... the Number of Windings of Wire present in their encircling Copper Coils.... Plus... Being modified by the Length or Distance they must Travel before they Mechanically either Close Relay Contacts or Close - Open a Valve Segments inside of any Device... say like an EGR (Exhausr Gas Re-Circulation) Valve that may have as many as THREE Separate Solenoids.

(4) Consequently, the Level of Sound created by their activation will vary depending upon what their intended functions are...Plus... How Rapidly and How Often they must perform their Activities.

(5) So... Relying upon any "Decibel Level" emanating out or any of these Solenoid Devices would be an unreliable way to figure out whether or not they are performing properly.

(6) However... If you can HEAR the Activation as it happens when directed by say... A Bi-Directional Instruction sent either from and to either the PCM during its timely Commands....or...coming from a Deliberate Test initiated from a GOOD Bi-Directional Scan Tool... If you can HEAR any activation...THAT should indicate that the Solenoid is Working.

(7) The Last Issue for Modern Electronically Controlled Vehicles ...is PMW...or Pulse Width Modulation frequently used to rapidly turn Solenoids On and Off depending upon the demands required by the PCM and the prevailing operational conditions going on.

(8) The entire reason for having these Fluid and Vapor Valves under the watchful gaze of the PCM is to prevent as much as possible, the escape of Fuel, Oil and Incomplete Combustion VOCs (Volatile Organic Compounds) from escaping and getting out into the Atmosphere. The idea is to either Capture and Store them temporarily inside of a Canister filled with pellets of Carbon... or simply re-route them directly back through the Air Stream and into the Engine to be burned as part of the normal Four Stroke Combustion Cycle.

(9) THINK ABOUT THE PHYSICAL SYSTEM AND ITS COMPONENTS IN YOUR MIND... and then logically examine ALL of them in the Order they Come On Line... and your Diagnosis will be Thorough, Complete... AND much more likely to put you in the EXACT Place where the Failure is occurring ... Like an Internally Stretched or Broken Wire that Touches when the SUV is COLD... but separates and Breaks the Circuit when the SUV is HOT...Or...Vice Versa!

(10) Try using a Simple, Inexpensive Short, Open or Broken Circuit Continuity Tracing Kit that will let you connect a Transceiver at the Circuit Suspevt Wire Point of Origin... and then LISTEN to the Second Portion of the Device as it Senses the Invisible... and allows you to Locate precisely where the Continuity of the activated Wire STOPS. Like THIS Kit that You can also use to Duplicate THIS Demonstration on Your TRAILBLAZER - ENVOY:

Available on Amazon via THIS GMT Nation Link:

Amazon.com

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Thanks. I was going to buy a tracer if I wasn't able to locate the fault but I got lucky by finding the broken fuse and the loose connector to the purge valve. It was not making a good connection. My thought now is that the OEM one probably had larger pins, so after 17 years and 400k+ miles, when I purchased the cheap replacement version, the connector pins were probably thinner and the connection was just loose enough on the pins to cause an intermittent connection. That's just a guess, but I think it makes sense. It's also why when I pulled the connector and tested for voltage it always had it. It wasn't the connector itself that was bad. It was the connection between the wire connector and the valve, if that makes sense. In any case, I took the connector apart, cleaned it and pinched the connectors so they'd make a solid connections when plugged in. The purge valve still seems loud to me, but for now it's working. These intermittent problems that you can't easily recreate, until you find a loose connection or a broken (not burnt) fuse are the toughest ones to diagnose. Thank You again for all of your help! Now on to P0171...sigh...